Case Report doi: 10.2176/nmc.cr2012-0233 Neurol Med Chir (Tokyo) 54, 841–844, 2014 Online October 21, 2013 Posterior Auricular - Bypass: A Rare Superficial Temporal Artery Variant with Well-developed Posterior Auricular Artery—Case Report

Joji Tokugawa,1 Yasuaki Nakao,1 Kentaro Kudo,1 Koji Iimura,1 Takanori Esaki,1 Takuji Yamamoto,1 and Kentaro Mori1

1Department of Neurosurgery, Juntendo University Shizuoka Hospital, Izunokuni, Shizuoka

Abstract The posterior auricular artery (PAA) is one of the branches of the , but is usually too small for use as a donor artery for middle cerebral artery (MCA) territory revascularization. An extremely unusual case of PAA-MCA anastomosis was performed in a patient requiring MCA territory revasculari- zation because the superficial temporal artery (STA) parietal branch was absent and the PAA was large enough. A 65-year-old man developed mild motor weakness in the right extremities caused by multiple small infarctions. Single photon emission computed tomography (CT) revealed deterioration of the vascu- lar reserve capacity in the left MCA area. Cerebral angiography showed severe stenosis in the C2 portion of the left , absence of the parietal branch of the left STA, and a well-developed PAA extending to the parietal area. The patient underwent STA (frontal branch)-MCA and PAA-MCA double anastomosis, and has suffered no stroke or transient ischemic attack. The STA with no bifurcation is known as a rare variation. The PAA also occurs with size variations but well-developed PAA is thought to be extremely rare. PAA can be used as a donor artery for MCA territory revascularization if the vessel size is suitable. Preoperative evaluation of the anatomy is mandatory for harvesting the .

Key words: carotid artery stenosis, extracranial-intracranial bypass, low-flow bypass, revascularization, stroke

Introduction absent and the PAA was unusually large, as if supplying the STA territory. The superficial temporal artery (STA) is the most widely used donor artery for middle cerebral artery (MCA) terri- Case Report tory revascularization, but if the STA cannot be used, other extracranial arteries such as the A 65-year-old man, with a long history of diabetes and (OA),1) contralateral STA (bonnet bypass),2,3) or arterial hypertension, suffered mild motor weakness in the right graft4,5) are well-known substitutes for the donor vessel. extremities. Magnetic resonance imaging revealed multiple The posterior auricular artery (PAA) is a small branch small infarctions in the left cerebral hemisphere (Fig. 1). that arises from the posterior aspect of the external Digital subtraction angiography showed a severe stenosis carotid artery, courses upward and backward, passes in the left C2 portion of the internal carotid artery (Fig. 2) through the groove between the cartilage of the auricle and a well-developed PAA extending to the parietal area and the mastoid process,6) and supplies a relatively small (Fig. 3A). Single photon emission CT using the double area of skin posterior to the ear.7) Conventional cerebral injection method8) showed the regional cerebrovascular angiography generally shows the PAA as slender and reserve capacity was reduced in the left MCA territory thus too small for use as a donor artery. We treated a (Table 1). Although the patient was receiving adequate patient requiring MCA territory revascularization with a volume expansion and antiplatelet therapies, transient PAA-MCA bypass because the STA parietal branch was ischemic attacks such as sensory disturbance and/or mild motor weakness in the right were frequently observed. Received June 25, 2012; Accepted December 6, 2012 As the patient was thought to be in a hemodynamically

841 842 J. Tokugawa et al.

compromised state, revascularization for the left MCA territory was performed approximately 2 months after the initial onset. The patient underwent STA (frontal branch)-MCA and PAA-MCA double anastomosis. The STA frontal branch and PAA were traced with the Doppler probe passed over the skin before the surgery (Fig. 4). The skin inci- sion was started in front of the left ear to expose the proximal portion of the STA. The incision was gently curved posteriorly along the upper edge of the ear until just above the PAA. The PAA was harvested by the cut down method. After an adequate length of the PAA was Fig. 1 Diffusion-weighted magnetic resonance (MR) image exposed (approximately as far as the linear temporalis), demonstrating multiple fresh infarctions in both the cortical the incision was gently curved to the frontal skin towards and subcortical areas of the left cerebral hemisphere, indicating the midline. After reflecting the skin flap, the STA frontal the duplex of hemodynamic compromise and artery-to-artery branch was dissected from the bed as far as the proximal embolism. portion already exposed earlier. A small craniotomy was made over the sylvian fissure. The recipient branches of the MCA were identified underneath the arachnoid membrane of the sylvian fissure according to the size of the donor and recipient arteries. The STA and PAA were anastomosed with 10-0 nylon to the frontal and temporal branches of the M3 portion, respectively. Blood flow in both the donor and recipient arteries was confirmed with the Doppler probe. The postoperative course was unremarkable. No skin problems were observed. Postoperative angiography showed good patency of the anastomoses (Fig. 3B). The patient has suffered no stroke or transient ischemic attack.

Discussion

The PAA has received little attention in the neurosur- gical field. Even in standard neuroradiological textbooks, discussion of the PAA is limited. In contrast, the PAA is Fig. 2 Digital subtraction angiogram of the left common carotid well-documented in the plastic and reconstructive surgery artery, oblique view, clearly demonstrating severe stenosis field because the AAP is frequently used for a pedicled (arrow) in the left C2 portion. skin flap.9) This artery arises from the posterior aspect

Fig. 3 Pre- (A) and postoperative (B) lateral external carotid arterio- grams demonstrating the frontal branch of the superficial temporal artery (STA, white arrows) and posterior auricular artery (black arrows). Note the absence of the parietal branch of the STA in A. Patent anastomoses and sufficient distal flow are demonstrated in B. The black dot indicates the external auditory canal.

Neurol Med Chir (Tokyo) 54, October, 2014 PAA-MCA Anastomosis 843

Table 1 Cerebral blood flow findings on single photon emission computed tomography

Rest (mL/min/100 g) Acetazolamide (mL/min/100 g) Vascular Reserve Capacity (%) Right Left Right Left Right Left ACA 53.79 53.83 48.30 54.17 –10.21 0.63 MCA 55.76 54.26 87.00 60.00 56.03 10.58 M2 anterior 56.21 56.21 85.78 59.16 52.61 5.25 M2 posterior 56.00 53.79 90.01 62.55 60.73 16.29

ACA: anterior cerebral artery, MCA: middle cerebral artery.

over a 5-year period, but no detailed description was available.19) The other patients were treated by STA-MCA anastomoses. Recently, PAA-STA anastomosis was used in repeat surgery for moyamoya disease.7) In their case, the STA and OA had already been used as the donor arteries in previous surgeries, and the changed hemodynamic status may have affected the blood supply to the PAA. The PAA is usually not a candidate donor artery because of the slender appearance on conventional angiography, but neurosurgeons should be aware of the variation in size as in the present case. The present case shows that the PAA can be used as a donor artery for MCA territory revascularization if the vessel size is suitable. As the branches of the external carotid artery may have some variations, as in our case, meticulous preoperative study is necessary for planning of the revascularization. Fig. 4 Photograph showing the tracing of the superficial temporal artery frontal branch (white arrows) and posterior Conflicts of Interest Disclosure auricular artery (black arrows) on the skin, and the skin inci- sion (arrowheads) marked according to the paths of the arteries. The authors have no funding and financial interest. References of the external carotid artery and passes dorsal to the external auditory canal, and has a consistent cutaneous 1) spetzler R, Chater N: Occipital arteryEmmiddle cerebral distribution based on a cadaver study.10) However, the artery anastomosis for cerebral artery occlusive disease. PAA supplies not only the skin of the auricle and the Surg Neurol 2: 235–238, 1974 2) sanada Y, Kamiyama H, Iwaisako K, Yoshimine T, Kato A: postauricular skin, but also the extracranial facial nerve “Bonnet” bypass to proximal trunk of middle cerebral in the area.11,12) The PAA gives rise artery with a radial artery interposition graft: technical to the stylomastoid artery toward the facial nerve trunk in note. Minim Invasive Neurosurg 53: 203–206, 2010 70–80% of individuals. Therefore, surgeons must exercise 3) spetzler RF, Roski RA, Rhodes RS, Modic MT: The “bonnet great care when harvesting the artery. bypass”. Case report. J Neurosurg 53: 707–709, 1980 Anatomical studies of the STA have revealed variations 4) Büyükmumcu M, Güney O, Ustün ME, Uysal II, Seker M: or racial differences.13–18) A type of STA with no parietal Proximal superficial temporal artery to proximal middle branch was found among 50 autopsy specimens,14) and cerebral artery bypass using a radial artery graft: an anatomic another case was found in 27 specimens.16) This type approach. Neurosurg Rev 27: 185–188, 2004 looks quite similar to our case. However, these previous 5) Tachibana E, Suzuki Y, Harada T, Saito K, Gupta SK, Yoshida studies focused purely on the STA, with no description J: Bypass surgery using a radial artery graft for bilateral extracranial carotid arteries occlusion. Neurosurg Rev 23: of the PAA. This type is thought to be rare, based on 52–55, 2000 other anatomical studies which did not report this type 6) Newton TH, Potts DG: Radiology of the Skull and Brain, 13,15,18) of STA. Our present case is also thought to be a rare Book 2. St Louis, CV Mosby, 1974, p 1260 type with no parietal branch of the STA and a thick PAA 7) Horiuchi T, Kusano Y, Asanuma M, Hongo K: Posterior supplying the parietal region of the scalp. We could use auricular artery-middle cerebral artery bypass for additional this well-developed PAA as a donor artery. surgery of moyamoya disease. Acta Neurochir (Wien) 154: PAA-STA anastomosis was reported in two of 65 cases 455–456, 2012 Neurol Med Chir (Tokyo) 54, October, 2014 844 J. Tokugawa et al.

8) mori K, Maeda M, Asegawa S, Masuda Y, Takeoka K: A study of the superficial temporal artery.Neurosurgery 16: new technique for quantitative imaging of cerebrovascular 786–790, 1985 reserve capacity using a double injection method with 15) mwachaka P, Sinkeet S, Ogeng’o J: Superficial temporal artery N-isopropyl-p-[123I]iodoamphetamine. Neuroimage 3: among Kenyans: pattern of branching and its relation to 89–96, 1996 pericranial structures. Folia Morphol (Warsz) 69: 51–53, 9) moschella F, Cordova A, Pirrello R, De Leo A: The supra- 2010 auricular arterial network: anatomical bases for the use 16) Pinar YA, Govsa F: Anatomy of the superficial temporal of superior pedicle retro-auricular skin flaps.Surg Radiol artery and its branches: its importance for surgery. Surg Anat 24: 343–347, 2003 Radiol Anat 28: 248–253, 2006 10) mcKinnon BJ, Wall MP, Karakla DW: The vascular anatomy 17) stock AL, Collins HP, Davidson TM: Anatomy of the super- and angiosome of the posterior auricular artery. A cadaver ficial temporal artery.Head Neck Surg 2: 466–469, 1980 study. Arch Facial Plast Surg 1: 101–104, 1999 18) Tayfur V, Edizer M, Magden O: Anatomic bases of superficial 11) moreau S, Bourdon N, Salame E, Goullet de Rugy M, Babin temporal artery and temporal branch of facial nerve. J E, Valdazo A, Delmas P: Facial nerve: vascular-related Craniofac Surg 21: 1945–1947, 2010 anatomy at the stylomastoid foramen. Ann Otol Rhinol 19) gratzl O, Schmiedek P, Spetzler R, Steinhoff H, Marguth F: Laryngol 109: 849–852, 2000 Clinical experience with extra-intracranial arterial anasto- 12) upile T, Jerjes W, Nouraei SA, Singh SU, Kafas P, Sandison mosis in 65 cases. J Neurosurg 44: 313–324, 1976 A, Sudhoff H, Hopper C: The stylomastoid artery as an anatomical landmark to the facial nerve during parotid surgery: a clinico-anatomic study. World J Surg Oncol 7: 71, 2009 13) Chen TH, Chen CH, Shyu JF, Wu CW, Lui WY, Liu JC: Distri- Address reprint requests to: Joji Tokugawa, MD, PhD, Department bution of the superficial temporal artery in the Chinese of Neurosurgery, Juntendo University Shizuoka Hospital, adult. Plast Reconstr Surg 104: 1276–1279, 1999 1129 Nagaoka, Izunokuni, Shizuoka 410-2295, Japan. 14) marano SR, Fischer DW, Gaines C, Sonntag VK: Anatomical e-mail: [email protected]

Neurol Med Chir (Tokyo) 54, October, 2014